Silicon-Coated Negative Electrode for Internal Short Detection
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Solution Overview
Problem
Lithium secondary batteries face safety issues due to internal short-circuits, which can lead to rapid heat generation and thermal runaway, causing damage and explosions, and existing safety measures are inadequate in detecting and responding to such events in a timely manner.
Innovation Solution
A lithium secondary battery with a negative electrode having a carbon-based active material and a coating layer containing silicon-containing particles with a specific ratio of silicon to oxygen, providing a controlled volume resistance to prevent excessive heat generation and allow for early detection of internal shorts, coupled with a lithium secondary battery system that includes a sensing unit and controller to monitor and control charging/discharging, preventing thermal runaway.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If internal short-circuit occurs in lithium secondary battery, then heat generation increases rapidly, but safety is compromised leading to thermal runaway and explosion
Solution Approach 1:
A coating layer containing silicon-containing particles is introduced as an intermediary between the negative electrode active material and the electrolyte. This coating layer acts as a mediator that detects internal short-circuits through changes in electrical resistance and prevents thermal runaway by controlling heat generation, thereby resolving the contradiction between maintaining battery functionality and preventing safety hazards.
Solution Approach 2:
The patent replaces mechanical safety measures with an electrical detection system. By monitoring changes in electrical resistance of the coating layer, the system can detect internal short-circuits before they lead to thermal runaway, substituting physical/chemical safety mechanisms with electrical sensing and control.
2Reliability
If conventional safety measures are used, then basic protection is provided, but early detection of internal shorts is not achieved in timely manner
Solution Approach 1:
The coating layer is pre-applied to the negative electrode before battery assembly, establishing a detection mechanism in advance. When an internal short occurs, the coating layer's electrical resistance changes immediately, providing early warning before thermal runaway begins, thus enabling timely response and preventing catastrophic failure.
3Reliability
If coating layer with silicon-containing particles is applied, then heat generation is controlled and safety is improved, but device structure becomes more complex
Solution Approach 1:
The coating layer is formed as a composite material combining silicon-containing particles with a binder material. This composite structure provides both the electrical detection capability (through silicon particles) and the structural integrity (through binder), achieving thermal safety and detection functionality while maintaining a relatively simple layered structure that can be integrated into existing battery manufacturing processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces heat generation and allows for early detection of internal shorts, preventing thermal runaway and ensuring the safety of the battery and adjacent cells by controlling the charging/discharging process before thermal runaway occurs.
Implementation Method 1
a volume resistance of the negative electrode is about 1.0×10−4 Ω·cm to 1.0 Ω·cm
Implementation Method 2
Lithium secondary batteries generate electric energy through oxidation and reduction reactions when lithium ions are intercalated/deintercalated at a positive electrode and a negative electrode
Implementation Method 3
a sensing unit electrically coupled to an electrode of each lithium secondary battery included in the cell assemblies to individually measure at least one type of electricity amount between an electric voltage and an electric current
Data Source
AI summary
A lithium secondary battery includes: a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode. In the negative electrode, a negative electrode active layer containing a carbon-based negative electrode active material and a coating layer containing silicon-containing particles are sequentially located on a negative electrode current collector, and a volume resistance of the negative electrode is about 6.0×10−3 Ω·cm to 1.0Ω·cm.